Start Date

November 2016

End Date

November 2016

Location

MSE 103

Type of Presentation

Oral Talk

Abstract

Reducing the size of piezoelectric energy harvesting devices – progressing from bulk materials, through the micro scale, and now into the nanoscale – has attracted much interest in new size-based classifications of clean energy sources converting ambient, attenuated mechanical energy, that would otherwise be wasted, into electrical energy. Compared to the macro devices, nanofibrous based transducer materials, with their exclusively large surface area-to-volume ratio, have shown enhanced piezoelectric properties. Electrospinning was used to fabricate a nanofibrous structures of Barium Titanate (BaTiO3) by jetting a solution of barium and titanium precursors dissolved with poly (vinyl pyrrolidone) (PVP) via applied voltage. Three separate full-factorial design of experiments (DOEs) (one 3-level, two 2-levels) were conducted to control and optimize the process to minimize fiber diameter with the least amount of beading defects. The three factor design focused on the optimization of the solution properties (viscosity, electrical conductivity, surface tension), one of the two factor DOE was focused on the electrospinning parameters (voltage, flow rate), while the other two factor DOE was focused on the electrospinning environmental conditions (temperature, absolute humidity). Low temperature and low absolute humidity produced the smallest fibers with a consistent diameter and minimal beading defects. Scanning electron microscopy (SEM) was utilized to characterize the morphology and diameter of the as-spun nanofibers, X-Ray Diffraction was used to determine crystal structure and average grain size, and Piezoresponse Force Microscopy (PFM) was used to measure the piezoelectric response. Micrographs of our best results showed as-spun nanofibers with an average diameter of 74.6 ± 15 nm with minimal beading and calcinated fibers having a diameter as low as 48 nm. The fibers were analyzed to confirm its perovskite crystal structure and calculate an average d33 piezoelectric response of 37.03 ± 5.34 pm/V with a peak value of 49.6 pm/V.

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Reducing the size of piezoelectric energy harvesting devices – progressing from bulk materials, through the micro scale, and now into the nanoscale – has attracted much interest in new size-based classifications of clean energy sources converting ambient, attenuated mechanical energy, that would otherwise be wasted, into electrical energy. Compared to the macro devices, nanofibrous based transducer materials, with their exclusively large surface area-to-volume ratio, have shown enhanced piezoelectric properties. Electrospinning was used to fabricate a nanofibrous structures of Barium Titanate (BaTiO3) by jetting a solution of barium and titanium precursors dissolved with poly (vinyl pyrrolidone) (PVP) via applied voltage. Three separate full-factorial design of experiments (DOEs) (one 3-level, two 2-levels) were conducted to control and optimize the process to minimize fiber diameter with the least amount of beading defects. The three factor design focused on the optimization of the solution properties (viscosity, electrical conductivity, surface tension), one of the two factor DOE was focused on the electrospinning parameters (voltage, flow rate), while the other two factor DOE was focused on the electrospinning environmental conditions (temperature, absolute humidity). Low temperature and low absolute humidity produced the smallest fibers with a consistent diameter and minimal beading defects. Scanning electron microscopy (SEM) was utilized to characterize the morphology and diameter of the as-spun nanofibers, X-Ray Diffraction was used to determine crystal structure and average grain size, and Piezoresponse Force Microscopy (PFM) was used to measure the piezoelectric response. Micrographs of our best results showed as-spun nanofibers with an average diameter of 74.6 ± 15 nm with minimal beading and calcinated fibers having a diameter as low as 48 nm. The fibers were analyzed to confirm its perovskite crystal structure and calculate an average d33 piezoelectric response of 37.03 ± 5.34 pm/V with a peak value of 49.6 pm/V.